1. Field of the Invention
The present invention relates to a surface mount type stacked semiconductor device structure including a plurality of semiconductor devices each having a package and an outer lead, in which space for mounting the semiconductor devices on a system appliance can be reduced and capacity of the semiconductor devices can be increased.
2. Description of the Prior Art
Hereinafter, four examples of prior art memory modules in which their capacities are made twice are described with reference to FIGS. 28 to 31, respectively. Firstly, in a prior art memory module 130 shown in FIG. 28, a semiconductor device 132 formed by an ordinary single chip is mounted on each of opposite faces of a printed wiring board 133 by outer leads 132a extending straight horizontally from opposite sides of the semiconductor device 132. The memory module 130 is mounted on a substrate 120 for a system appliance by solder balls 39 provided on a lower face of the printed wiring board 133.
Secondly, in a conventional memory module 140 shown in FIG. 29, two packages 142 each having gull wing outer leads or L type outer leads 144 are stacked on each other through a small connecting substrate 143. By soldering the L type outer lead 144 of the lower package 142 to the substrate 120 for the system appliance, the memory module 140 is mounted on the substrate 120 for the system appliance.
Thirdly, in a known memory module 150 shown in FIG. 30, L type outer leads 153 of a lower package 152 and outer leads 155 of an upper package 154 are directly connected to each other. By soldering the L type outer leads 153 of the lower package 152 to the substrate 120 for the system appliance, the memory module 150 is mounted on the substrate 120 for the system appliance.
Fourthly, in a prior art memory module 160 shown in FIG. 31, two semiconductor chips 163 are stacked on each other in a resinous package 162. By soldering L type outer leads 164 of the resinous package 162 to the substrate 120 for the system appliance, the memory module 160 is mounted on the substrate 120 for the system appliance.
However, in the constructions of the above described prior art memory modules and in the methods of mounting the above mentioned prior art memory modules on the substrate 120 for the system appliance, such drawbacks are incurred that the number of stacking of the semiconductor devices 132 in FIG. 28, the number of stacking of the packages 142 in FIG. 29, the number of stacking of the packages 152 and 154 in FIG. 30 and the number of stacking of the semiconductor chips 163 in the resinous package 162 in FIG. 31 are physically limited and reduction of area for mounting the memory module on the substrate 120 for the system appliance is restricted by size of these semiconductor devices.
Accordingly, an essential object of the present invention is to provide, with a view to eliminating the above mentioned drawbacks of prior art, a surface mount type stacked semiconductor device structure including a plurality of semiconductor devices, in which space for mounting the semiconductor devices on a system appliance can be reduced and capacity of the semiconductor devices can be increased.
In order to accomplish this object of the present invention, a stacked semiconductor device structure according to the present invention comprises: a plurality of semiconductor modules each of which includes a substrate and at least one semiconductor device mounted on the substrate; a stacking means for stacking the semiconductor modules on one another; and a surface mount means for surface mounting on a further substrate for a system appliance the semiconductor modules stacked on one another by the stacking means.